]> git.ipfire.org Git - thirdparty/git.git/commitdiff
fsmonitor--daemon: implement 'run' command
authorJeff Hostetler <jeffhost@microsoft.com>
Fri, 25 Mar 2022 18:02:53 +0000 (18:02 +0000)
committerJunio C Hamano <gitster@pobox.com>
Fri, 25 Mar 2022 23:04:15 +0000 (16:04 -0700)
Implement `run` command to try to begin listening for file system events.

This version defines the thread structure with a single fsmonitor_fs_listen
thread to watch for file system events and a simple IPC thread pool to
watch for connection from Git clients over a well-known named pipe or
Unix domain socket.

This commit does not actually do anything yet because the platform
backends are still just stubs.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
builtin/fsmonitor--daemon.c
fsmonitor--daemon.h [new file with mode: 0644]

index 5e3178b8bddbc6c421dfc9860521dc2f4aacfaf0..5591339399a8ca94d7934124568580932be6418e 100644 (file)
@@ -3,16 +3,52 @@
 #include "parse-options.h"
 #include "fsmonitor.h"
 #include "fsmonitor-ipc.h"
+#include "compat/fsmonitor/fsm-listen.h"
+#include "fsmonitor--daemon.h"
 #include "simple-ipc.h"
 #include "khash.h"
 
 static const char * const builtin_fsmonitor__daemon_usage[] = {
+       N_("git fsmonitor--daemon run [<options>]"),
        N_("git fsmonitor--daemon stop"),
        N_("git fsmonitor--daemon status"),
        NULL
 };
 
 #ifdef HAVE_FSMONITOR_DAEMON_BACKEND
+/*
+ * Global state loaded from config.
+ */
+#define FSMONITOR__IPC_THREADS "fsmonitor.ipcthreads"
+static int fsmonitor__ipc_threads = 8;
+
+#define FSMONITOR__ANNOUNCE_STARTUP "fsmonitor.announcestartup"
+static int fsmonitor__announce_startup = 0;
+
+static int fsmonitor_config(const char *var, const char *value, void *cb)
+{
+       if (!strcmp(var, FSMONITOR__IPC_THREADS)) {
+               int i = git_config_int(var, value);
+               if (i < 1)
+                       return error(_("value of '%s' out of range: %d"),
+                                    FSMONITOR__IPC_THREADS, i);
+               fsmonitor__ipc_threads = i;
+               return 0;
+       }
+
+       if (!strcmp(var, FSMONITOR__ANNOUNCE_STARTUP)) {
+               int is_bool;
+               int i = git_config_bool_or_int(var, value, &is_bool);
+               if (i < 0)
+                       return error(_("value of '%s' not bool or int: %d"),
+                                    var, i);
+               fsmonitor__announce_startup = i;
+               return 0;
+       }
+
+       return git_default_config(var, value, cb);
+}
+
 /*
  * Acting as a CLIENT.
  *
@@ -57,15 +93,198 @@ static int do_as_client__status(void)
        }
 }
 
+static ipc_server_application_cb handle_client;
+
+static int handle_client(void *data,
+                        const char *command, size_t command_len,
+                        ipc_server_reply_cb *reply,
+                        struct ipc_server_reply_data *reply_data)
+{
+       /* struct fsmonitor_daemon_state *state = data; */
+       int result;
+
+       /*
+        * The Simple IPC API now supports {char*, len} arguments, but
+        * FSMonitor always uses proper null-terminated strings, so
+        * we can ignore the command_len argument.  (Trust, but verify.)
+        */
+       if (command_len != strlen(command))
+               BUG("FSMonitor assumes text messages");
+
+       trace2_region_enter("fsmonitor", "handle_client", the_repository);
+       trace2_data_string("fsmonitor", the_repository, "request", command);
+
+       result = 0; /* TODO Do something here. */
+
+       trace2_region_leave("fsmonitor", "handle_client", the_repository);
+
+       return result;
+}
+
+static void *fsm_listen__thread_proc(void *_state)
+{
+       struct fsmonitor_daemon_state *state = _state;
+
+       trace2_thread_start("fsm-listen");
+
+       trace_printf_key(&trace_fsmonitor, "Watching: worktree '%s'",
+                        state->path_worktree_watch.buf);
+       if (state->nr_paths_watching > 1)
+               trace_printf_key(&trace_fsmonitor, "Watching: gitdir '%s'",
+                                state->path_gitdir_watch.buf);
+
+       fsm_listen__loop(state);
+
+       trace2_thread_exit();
+       return NULL;
+}
+
+static int fsmonitor_run_daemon_1(struct fsmonitor_daemon_state *state)
+{
+       struct ipc_server_opts ipc_opts = {
+               .nr_threads = fsmonitor__ipc_threads,
+
+               /*
+                * We know that there are no other active threads yet,
+                * so we can let the IPC layer temporarily chdir() if
+                * it needs to when creating the server side of the
+                * Unix domain socket.
+                */
+               .uds_disallow_chdir = 0
+       };
+
+       /*
+        * Start the IPC thread pool before the we've started the file
+        * system event listener thread so that we have the IPC handle
+        * before we need it.
+        */
+       if (ipc_server_run_async(&state->ipc_server_data,
+                                fsmonitor_ipc__get_path(), &ipc_opts,
+                                handle_client, state))
+               return error_errno(
+                       _("could not start IPC thread pool on '%s'"),
+                       fsmonitor_ipc__get_path());
+
+       /*
+        * Start the fsmonitor listener thread to collect filesystem
+        * events.
+        */
+       if (pthread_create(&state->listener_thread, NULL,
+                          fsm_listen__thread_proc, state) < 0) {
+               ipc_server_stop_async(state->ipc_server_data);
+               ipc_server_await(state->ipc_server_data);
+
+               return error(_("could not start fsmonitor listener thread"));
+       }
+
+       /*
+        * The daemon is now fully functional in background threads.
+        * Wait for the IPC thread pool to shutdown (whether by client
+        * request or from filesystem activity).
+        */
+       ipc_server_await(state->ipc_server_data);
+
+       /*
+        * The fsmonitor listener thread may have received a shutdown
+        * event from the IPC thread pool, but it doesn't hurt to tell
+        * it again.  And wait for it to shutdown.
+        */
+       fsm_listen__stop_async(state);
+       pthread_join(state->listener_thread, NULL);
+
+       return state->error_code;
+}
+
+static int fsmonitor_run_daemon(void)
+{
+       struct fsmonitor_daemon_state state;
+       int err;
+
+       memset(&state, 0, sizeof(state));
+
+       pthread_mutex_init(&state.main_lock, NULL);
+       state.error_code = 0;
+       state.current_token_data = NULL;
+
+       /* Prepare to (recursively) watch the <worktree-root> directory. */
+       strbuf_init(&state.path_worktree_watch, 0);
+       strbuf_addstr(&state.path_worktree_watch, absolute_path(get_git_work_tree()));
+       state.nr_paths_watching = 1;
+
+       /*
+        * We create and delete cookie files somewhere inside the .git
+        * directory to help us keep sync with the file system.  If
+        * ".git" is not a directory, then <gitdir> is not inside the
+        * cone of <worktree-root>, so set up a second watch to watch
+        * the <gitdir> so that we get events for the cookie files.
+        */
+       strbuf_init(&state.path_gitdir_watch, 0);
+       strbuf_addbuf(&state.path_gitdir_watch, &state.path_worktree_watch);
+       strbuf_addstr(&state.path_gitdir_watch, "/.git");
+       if (!is_directory(state.path_gitdir_watch.buf)) {
+               strbuf_reset(&state.path_gitdir_watch);
+               strbuf_addstr(&state.path_gitdir_watch, absolute_path(get_git_dir()));
+               state.nr_paths_watching = 2;
+       }
+
+       /*
+        * Confirm that we can create platform-specific resources for the
+        * filesystem listener before we bother starting all the threads.
+        */
+       if (fsm_listen__ctor(&state)) {
+               err = error(_("could not initialize listener thread"));
+               goto done;
+       }
+
+       err = fsmonitor_run_daemon_1(&state);
+
+done:
+       pthread_mutex_destroy(&state.main_lock);
+       fsm_listen__dtor(&state);
+
+       ipc_server_free(state.ipc_server_data);
+
+       strbuf_release(&state.path_worktree_watch);
+       strbuf_release(&state.path_gitdir_watch);
+
+       return err;
+}
+
+static int try_to_run_foreground_daemon(void)
+{
+       /*
+        * Technically, we don't need to probe for an existing daemon
+        * process, since we could just call `fsmonitor_run_daemon()`
+        * and let it fail if the pipe/socket is busy.
+        *
+        * However, this method gives us a nicer error message for a
+        * common error case.
+        */
+       if (fsmonitor_ipc__get_state() == IPC_STATE__LISTENING)
+               die(_("fsmonitor--daemon is already running '%s'"),
+                   the_repository->worktree);
+
+       if (fsmonitor__announce_startup) {
+               fprintf(stderr, _("running fsmonitor-daemon in '%s'\n"),
+                       the_repository->worktree);
+               fflush(stderr);
+       }
+
+       return !!fsmonitor_run_daemon();
+}
+
 int cmd_fsmonitor__daemon(int argc, const char **argv, const char *prefix)
 {
        const char *subcmd;
 
        struct option options[] = {
+               OPT_INTEGER(0, "ipc-threads",
+                           &fsmonitor__ipc_threads,
+                           N_("use <n> ipc worker threads")),
                OPT_END()
        };
 
-       git_config(git_default_config, NULL);
+       git_config(fsmonitor_config, NULL);
 
        argc = parse_options(argc, argv, prefix, options,
                             builtin_fsmonitor__daemon_usage, 0);
@@ -73,6 +292,13 @@ int cmd_fsmonitor__daemon(int argc, const char **argv, const char *prefix)
                usage_with_options(builtin_fsmonitor__daemon_usage, options);
        subcmd = argv[0];
 
+       if (fsmonitor__ipc_threads < 1)
+               die(_("invalid 'ipc-threads' value (%d)"),
+                   fsmonitor__ipc_threads);
+
+       if (!strcmp(subcmd, "run"))
+               return !!try_to_run_foreground_daemon();
+
        if (!strcmp(subcmd, "stop"))
                return !!do_as_client__send_stop();
 
diff --git a/fsmonitor--daemon.h b/fsmonitor--daemon.h
new file mode 100644 (file)
index 0000000..3009c1a
--- /dev/null
@@ -0,0 +1,34 @@
+#ifndef FSMONITOR_DAEMON_H
+#define FSMONITOR_DAEMON_H
+
+#ifdef HAVE_FSMONITOR_DAEMON_BACKEND
+
+#include "cache.h"
+#include "dir.h"
+#include "run-command.h"
+#include "simple-ipc.h"
+#include "thread-utils.h"
+
+struct fsmonitor_batch;
+struct fsmonitor_token_data;
+
+struct fsmonitor_daemon_backend_data; /* opaque platform-specific data */
+
+struct fsmonitor_daemon_state {
+       pthread_t listener_thread;
+       pthread_mutex_t main_lock;
+
+       struct strbuf path_worktree_watch;
+       struct strbuf path_gitdir_watch;
+       int nr_paths_watching;
+
+       struct fsmonitor_token_data *current_token_data;
+
+       int error_code;
+       struct fsmonitor_daemon_backend_data *backend_data;
+
+       struct ipc_server_data *ipc_server_data;
+};
+
+#endif /* HAVE_FSMONITOR_DAEMON_BACKEND */
+#endif /* FSMONITOR_DAEMON_H */